In the food industry, heterogeneous admixtures are very often processed, that is to say, admixtures containing a plurality of phases which are mixed with each other, the term heterogeneous admixtures in the context of the present description being intended to be understood to refer to liquid or fluid admixtures containing solid particles which have various dimensions and which are dispersed within the liquid phase.
In the sector of filtration of liquids with solid contents which are dispersed therein, and in particular in the oenological sector, it is a fundamental and strategic requirement to be able to filter and purify admixtures and solutions with different corpuscular contents by percentage within short times and obtaining high final purity values.
In that sector, it is known to use tangential filtration separation units.
That technology is particularly versatile for separating the desired dimensions of suspended solid in a selective manner.
In the sector for processing wines, it is necessary to filter and purify a predetermined admixture in respect of undesired particles, solid contaminants and microorganisms, at the same time maintaining the protein and colloid structure in an unchanged state.
It is further fundamental in all the processing processes for oenological suspensions to control and where applicable to reduce the processing temperatures of those admixtures because excessive fluctuations of that parameter could lead to variations and/or adulterations of the organoleptic components contained.
However, that filtration and purification technology has the intrinsic limitation of becoming more effective as the dimensions of the corpuscular components become increasingly similar to the ideal dimensions for the interaction with the holes of the membrane contained in the system for tangential filtration, and the quantities of solid material in suspension do not exceed predetermined values.
As a result, among the most significant critical states correlated with the industrial use of that technology, there are frequent blockages of the filters which involve a decrease in the performance of the tangential filters and a resultant increase in the general process times as a result of the large number of suspensions of the filtration processes which are dedicated to the cleaning and restoration steps of the filters.
That disadvantage is particularly evident in the oenological industry in which the heterogeneous admixtures to be processed comprise significant quantities of solid portions, such as grapes and sediments, which have dimensions which may also be quite different from each other and which are very variable, and with rheologically different behaviours.
Those admixtures cause frequent, problematic blockages of the sieve-like filters which are normally used in those technological contexts.
Therefore, it is often necessary to stop the processing process in order to clean the filters in respect of the solid portions.
Furthermore, tangential filters are not suitable for processing heterogeneous admixtures having solid particles with great dimensions because they could permanently damage the membranes of the tangential filters.
Tangential filters are not suitable for processing admixtures having high percentage rates of solid portions therein.
Another disadvantage of filtration with tangential filters is the undesirable increase of the temperature of the heterogeneous admixture being processed during the filtration which involves the risk of varying the organoleptic properties and characteristics of the admixture.
Therefore, it can readily be seen that, for the above-mentioned reasons, processing admixtures having a high content of solid components in plants having technologies which use tangential filters is definitely not recommended.